You're talking about dropping one third of your entire body weight, so go in knowing that not only are you going to lose some fat, but your also going to be losing a lot of muscle mass and definition. To even come close to that kind of weight loss you need to seriously look into training and eating much like a VERY SERIOUS long distance runner, as they are about the only people who can weigh that much and look in shape. I hope your giving yourself a lot of time to accomplish this, and make sure you drink at least a gallon of water a day.